32 THE STORY OF THE PLANTS* 



many more again next season. Indeed, if an 

 annual plant had only two seeds, each of which 

 lived and produced two more, and so on con- 

 tinually, in twenty years its descendants would 

 amount to no less than a million. From all this 

 it necessarily results that a Struggle for Exis- 

 tence must take place among plants ; they fight 

 with one another for the soil, the rain, the 

 carbon, the sunshine. 



Again, take such a wild flower as this very red 

 campion. Why has it light pink petals? The 

 reason is, to attract the insects which fertilise 

 it. Flowers, in which the pollen is carried by 

 the wind, never have brilliant or conspicuous 

 blossoms ; but flowers which are fertilised by 

 insects have almost always coloured petals to tell 

 the insects where to find the honey. How did 

 this come about? In this way, I imagine : Many 

 plants produce a sweet juice on their leaves for 

 example, the common laurel. This juice, which 

 is probably of no particular use to them, is very 

 greedily eaten by insects. Now suppose some 

 flower, by accident at first, happened to produce 

 such sweet juice near its stamens, which (as we 

 saw) are the organs for making pollen, and also 

 near its pistil, which contains its young seeds or 

 ovules. Then insects would naturally visit it to 

 eat this sweet juice, which we commonly call 

 honey. In eating it, they would dust themselves 

 over with the floury pollen, by pure accident, and 

 they would carry som,e of it away with them on 

 their heads and legs to the next flower they 

 visited. Chance would make them often rub off 

 the pollen and fertilise the flower ; and as such 



